Process of treating sludges obtained on refining petroleum oils with sulphuric acid



1931- M. D. MANN, R., ET AL 1,838,030

REATIN TAINED PROCESS O 1 G SLUDG 03 ON REFINING PE OLEUM OILS WIT ULP IC ACID Filed July l9 WATER Owner gvwemtow M47'7'HEWD. MAN/V7 1" AUGUST FOL/7Z5.

Patented Dec. 22, 1931 1 UNITED STATES PATENT OFFICE MATTHEW D. MANN, J'B., OF ROS ELLE, AND AUGUST HOLMES, OF NEWARK, NEW JERSEY, ASSIGNORS TO STANDARD OIL DEVELOPMENT COMPANY, A CORPORATION OF DELAWARE -PROCESS OF TREATING SLUDGES OBTAINED ON BEFINING PETROLEUM OILS WITH SULPHURIC ACID Application filed July 18, 1927. Serial No. 205,311.

This invention relates to a process for treating sludges obtained on refining etroleum oils with sulphuric acid and has or its object the more effective utilization thereof.

n In the manufacture of highly refined mineral oils, including white oils or medicinal oils, petroleum and/or petroleum distillates are agitated with fuming sulphuric acid or sulphuric anhydride. After agitation, the

mixture is permitted to stratify, two layers being formed. The bottom layer, consisting of a sludge containing unconsumed sulphuric acid and more or less sulphonated organic acids, is withdrawn. This treatment may be repeated a number of times, the sludges being withdrawn at the expiration of each treatment. They sometimes separate further into two layers, a less mobile layer consisting principally of organic material and a more mobile layer consisting principally of sulphuric acid, both of which will be hereinafter referred to generally as sludges. They differ materially from the sludges resulting from the usual refining of petroleum oils in which sulphuric acid, not fuming, is employed.-

The fuming acid sludges are characterized by a large solubility in water and are not readily amenable to the methods for the recovery of sulphuric acid which are applied to the usual refinery sludges.

Our invention relates to the treatment of the sludges, resulting from the agitation of petroleum oilswith fuming acid or sulphuric anhydride and comprises a process whereby such residues may be converted into valuable products by the application of heat with the simultaneous production of sulphur dioxide and a solid residue of organic material, containing sulphuric acid. The degree of heat to be applied for this purpose ordinarily ranges between 170 and 250 F. although higher temperatures may be employed. The solid residuum resulting from the application of heat has various qualities, depending upon the oil originally treated, the amount and strength of fuming acid used thereon and other factors. It may range from a dense, amorphous, asphaltic body of conchoidal fracture to a finely divided, porous, carbo- 50 naceousmass. The sulphuric acid is removed from the solid residuum preferably in granulated condition by leaching with water or dilute sulphuric acid. The solid material from which the sulphuric acid has been removed is suitable for fuel or may be converted into a decolorizing carbon.

The drawing, hereto annexed, is a diagrammatic vertical section through a form of apparatus for carrying out the preferred embodiment of our invention. The residues to be decomposed are pumped through valved pipe 1, into the steam jacketed agitator 2 which is equipped with rotatable shaft 3, ente-rin g through stufiing box 4, carrying paddle stirrer 5 and scroll 6. Treatment is instituted by the admission of steam through pipe 7 to the jacket 8 surrounding the agitator, water of condensation being withdrawn through valved pipe 9. During the treatment of the residues, the shaft 3 is rotated in such direction that the scroll 6 tends to lift the residues from the neck of the agitator. The steam in the jacket is under a pressure of 5 to 50.1,: gauge although other pressures may be employed. 75

The application of heat causes the evolution of' sulphur dioxide from the residues which passes ofi through vapor line 11 into the rectifying tower 12, condenser coil 19 and receptacles 16 and 23. The release valve 26 is preferably set to hold the system under a pressure such that sulphur dioxide will exist therein as a liquid, after cooling to ordinary temperatures. For this purpose, we preferably operate under a pressure of to 250 lbs. gauge.

As soon as the desired pressure obtains in the apparatus, cooling water is passed through partial condenser 13, the amount thereof being adjusted and maintained to produce rectification in the tower so that any water is fractionated out of the sulphur dioxide and passes through valved pipe 15 into receptacle 16. The sulphur dioxide passing away from the rectifying column through vapor line 14 is dry and of suitable uality for commercial utilization. It is con ensed in coil 19, by means of cooling water passing through condenser box 20 and flows through valve pipe 22 into receiver 23. Any non- 1"" condensible gases pass ofithrough release 9 existing in the autoclave 2, relieved by opening valve 116. The manhead 10, covering the lower part of the agitator is then removed.

The direction of rotation of the shaft 3 is reversed and so regulated that the scroll 6 will gradually discharge the heated residuum on to crushing rolls 28, of crusher 29. The

crushed material passes by gravity or any suitable conveyor into tank 30, equipped with rotatable shaft 31 and paddle mixer 32, actuated by any suitable means.

In this tank, the material is agitated with water or dilute sulphuric acid and the mixture is then discharged through pipe 33 controlled by valve 33a, into basket 34 of centrifugal 35. The basket is actuated by motor 36, operating through shaft 37 and is of course in rapid rotation during this period. The basket is of the perforated type, liquid passing through the perforations and solid material being retained at the inner periphery thereof. The sulphuric acid, free of solid material, collects in the trough 38 and flows through pipe 39 into one of containers 43, 44 or 45, controlled by valves 40, 41 and 42 respectively.

The solid material from which the sulphuric acid has been removed may be discharged into car 46 or may be washed .by spraying water or dilute sulphuric acid thereon by means of pipe 47 connecting with spray head 48, both controlled by valve 40. In our preferred method of se arating sulphuric acid from the heated resi ues, they are final- 1y washed with water in the centrifuge to form a weak sulphuric acid which is stored in tank 43. This weak sulphuric acid is em: plofyed for an intermediate wash in the centri uge of a succeeding batch of residues to form a sulphuric acid of medium strength 50 which is stored in tank 44. This medium strength sulphuric acid is then elevated by pump 50 into tank 30 in which it is contacted with the heated residues obtained from the next succeeding heat treatment and in this way forms a strong sulphuric acid which is separated by means of the centrifuge and passed into tank 45 from which it may be withdrawn for use. All succeeding batches are washed countercurrently with the weak sulphuric acids obtained from prior operations, resulting in a particularly effective extraction.

It will be understood that the specific apapparatus and is not limited to that shown or to the specific method of operation herein described. Various alternative procedures may be adopted within the scope of the appended claims in which it is my intention to claim broadly all novelty inherent in the invention.

We claim:

1. The process of decomposing sludges resulting from the treatment of etroleum oils with a material comprising ree sulphuric anhydride, which comprises heating the sludge to temperatures ranging between 170 and 250 F., and at no stage of the process above the latter temperature, whereby volatileproducts containing sulphur dio'xlde and a residuum of organic material containing sulphuric acid are produced.

2. Process according to claim 1 carried out at pressure of 50 to 250# gauge.

3. Process according toclaim 1, followed by extracting with.water or weak sulphuric acid the solidresiduum formed by heating and separation of the sulphuric acid so extracted therefrom.

4. The process of decomposing sludges resulting from the treatment of etroleum oils with a material comprising ree sulphuric anhydride, which comprises heating such residues to temperatures ranging between 170 and 250 F., and at no stage of the process above the latter temperature, whereby volatile products containing sulphur dioxide and a residuum of organic material containing sulphuric acid are produced, and conducting away and condensing the sulphur dioxide I so formed.

5. The process of decomposing sludges resulting from the treatment of'petroleum oils with a material comprising free sulphuric anhydride, which comprises heating same to temperatures ranging between 170 and 250 F., and at no stage of the process above the latter temperature, wherebyvolatile products containing sulphur dioxide and a residuum of organic material containing sulphuric acid are produced, conductin away and rectifying the sulphur dioxide so ormed to separate therefrom compounds of higher boiling point than sulphur dioxide, and condensing the vapors after separation to form liquid sulphur dioxide.

v 6. Process according to claim 1, with the additional step of conducting away the volatile products and extracting the residuum first with weak sulphuric acid obtained in previous operations then with water whereby medium and weak solutions of sulphuric acid are obtained.

MATTHEW D. MANN, JR. AUGUST HOLMES.

paratus shown is in illustration and that the process may be practiced with any suitable 

